JP2604197B2 - Liquid epoxy resin composition - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a liquid epoxy resin composition. More specifically, it is excellent in impregnation, flame retardancy and moisture resistance,
The present invention relates to a liquid epoxy resin composition capable of providing a homogeneous cured product.

[Prior art and its problems] Conventionally, an epoxy resin has been widely used as a casting resin for high-voltage electric parts and the like. In curing the epoxy resin composition, an acid anhydride-based curing agent and an amine-based curing accelerator such as a tertiary amine or imidazole are usually used in combination.

Epoxy resin compositions used as materials for high-voltage electrical components require various properties such as insulation, impregnation, moisture resistance, easy curing, thermal shock, thermal conductivity, and flame retardancy. At present, their characteristics are comprehensively evaluated.

Generally, in order to improve the impact resistance, flame retardancy, and thermal conductivity of the resin composition, it is effective to add a large amount of an inorganic filler to the resin composition. As the viscosity increases, the viscosity of the resin composition increases, and as a result, it becomes difficult to impregnate and cast high piezoelectric components, and in extreme cases, imperfect impregnation results in corona deterioration, dielectric breakdown, etc. of the high piezoelectric components. This can cause problems.

The impregnating property of the epoxy resin composition is an important property, especially for high-voltage electrical components, and in order to improve the impregnating property of the transformer coil, the epoxy resin is mixed with various diluents such as esters and monoglycidyl ethers. Methods have been proposed to reduce the viscosity of the composition. However, a large amount of diluent is required for lowering the viscosity, and if the amount is too large, the heat-resistant temperature decreases or the water absorption rate increases,
Due to problems such as a decrease in moisture resistance, there is a limit to the amount added, and it cannot be said that the intended purpose can be sufficiently achieved.

The present inventors have found that even if a large amount of an inorganic filler is blended, a low viscosity is maintained, the impregnation property of electric parts and the like is good, and the sedimentation of the inorganic filler is suppressed, so that a homogeneous cured product is obtained. As a result of intensive studies to provide an epoxy resin composition capable of obtaining an epoxy resin composition, it has been found that an epoxy resin composition containing a certain compound in a specific liquid epoxy resin composition has predetermined characteristics. The present invention has been completed based on such knowledge.

Another object of the present invention is to provide an epoxy resin composition having good properties such as insulation, moisture resistance, easy curing, thermal shock resistance, and thermal conductivity.

Another object of the present invention is to provide an epoxy resin composition which retains the above-mentioned various properties and is excellent in flame retardancy.

[Means for Solving the Problems] The liquid epoxy resin composition according to the present invention comprises the following components (A) to (E) as essential components, and optionally a component (F). Features.

(A) an epoxy resin, (B) a liquid carboxylic anhydride, (C) an inorganic filler containing hydrated alumina and calcium carbonate, (D) an organic phosphine compound, and (E) a compound represented by (1) to (8). One or two of
A mixture of more than one species, (7) Dimer acid (8) Rosin [In each of the above general formulas, R ¹ is a linear or branched C 9 -C optionally having a hydroxyl group.
24 represents an alkyl group or an alkenyl group. R ² represents a linear or branched alkyl group having 6 to 26 carbon atoms, a cycloalkyl group, a cycloalkenyl group, or an aryl group. R ³ , R ⁴ and R ⁵ are each a hydrogen atom or a linear or branched carbon atom having 1 to 4 carbon atoms which may be the same or different.
26 represents an alkyl group, alkenyl group, cycloalkyl group, cycloalkenyl group, aryl group and alkylene oxide adduct thereof. However, all of R ³ , R ⁴ and R ⁵ are not hydrogen atoms. R ⁶ and R ⁷ may be the same or different, and each represents a hydrogen atom, a linear or branched alkyl group or alkenyl group having 1 to 24 carbon atoms which may have a hydroxyl group. Express. (F) One or a mixture of two or more of an antimony compound, a halogen compound and a phosphorus compound.

The epoxy resin (A) used in the present invention is not particularly limited, and those conventionally known in this field can be widely used. Specifically, bisphenol A type epoxy resin,
Glycidyl ether type epoxy resin such as bisphenol F type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, glycidyl ester type epoxy resin, glycidylamine type epoxy resin, cycloaliphatic epoxy resin, heterocyclic epoxy resin, Examples thereof include a halogenated epoxy resin, a glycidyl ether resin obtained from a mono- to tetravalent aliphatic alcohol, and a glycidyl ether resin obtained from a polyether polyol. These epoxy resins are used alone or in combination of two or more.

If necessary, phenylglycidyl ether, 2-
Liquid monoepoxy compounds such as ethylhexyl glycidyl ether, dibromocresyl glycidyl ether, 2,4,6-tribromophenyl glycidyl ether and glycidyl neoate can also be added.

In order to enhance the impregnating property to high-voltage electric components and the like, it is preferable to use a liquid epoxy resin at room temperature, and its epoxy equivalent is recommended to be about 300 at the maximum. With an epoxy resin having an epoxy equivalent greater than this, the resulting resin composition has a high viscosity, and the intended object of the present invention is hardly achieved. In addition, even if it is a solid epoxy resin at room temperature, any epoxy resin that can be liquefied by using a liquid epoxy resin or a diluent in combination within the allowable range in terms of physical properties can be used without any problem.

As the liquid carboxylic anhydride (B) used as the epoxy resin curing agent in the present invention, a compound that is liquid at 25 ° C. is recommended. Specific examples of such carboxylic anhydrides include methyltetrahydrophthalic anhydride such as 3-methyltetrahydrophthalic anhydride and 4-methyltetrahydrophthalic anhydride (hereinafter abbreviated as “Me-THPA”), 3- Methylhexahydrophthalic anhydride (hereinafter abbreviated as "Me-HHPA") such as methylhexahydrophthalic anhydride and 4-methylhexahydrophthalic anhydride, methylnadic anhydride, dodecenyl succinic anhydride and structures thereof Mix and modify with isomers or geometric isomers, mixed with solid anhydrides at room temperature such as hexahydrophthalic anhydride, tetrahydrophthalic anhydride, phthalic anhydride, trimellitic anhydride, benzophenonetetracarboxylic anhydride. And liquefied. The carboxylic anhydrides may be used alone or in combination of two or more. Among these carboxylic acids, Me-THPA and Me-
HHPA is preferable because of its low viscosity, and among them, a mixture of 3-Me-THPA and a carboxylic anhydride containing 50% by weight or more thereof is particularly preferable because of its low viscosity.

The amount of the carboxylic acid anhydride is usually about 0.5 to 1.5 equivalents per equivalent of epoxy of the epoxy resin used,
Preferably, it is about 0.7 to 1.0 equivalent. If the amount is less than this range, heat resistance, electrical properties, mechanical strength, etc., will be reduced. Conversely, if the amount is more than the above range, moisture resistance and electrical properties tend to decrease, which is not preferable.

The inorganic filler (C) applied in the present invention contains hydrated alumina and calcium carbonate as essential components.

The hydrated alumina is a powder represented by Al ₂ O ₃ .3H ₂ O, and is not particularly limited, but has a particle diameter of about 1 to 30 μ (measured on a weight basis by a sedimentation method). Appropriate.

The calcium carbonate according to the present invention is not limited to heavy calcium carbonate, light calcium carbonate, gourd flour and the type thereof, and the particle size thereof is not particularly limited. A particle size of about (measured on a weight basis) is appropriate.

When both the hydrated alumina and calcium carbonate are smaller than the above-mentioned particle diameter, the viscosity of the system becomes high, and conversely, when the particle diameter is large, there is a tendency for sedimentation during storage or heat curing, which is inconvenient.

The amount of hydrated alumina is preferably about 65 to 190 parts by weight, based on 100 parts by weight of the epoxy resin, and the amount of calcium carbonate is preferably about 40 to 150 parts by weight, based on 100 parts by weight of the epoxy resin. . In particular, the total amount of hydrated alumina and calcium carbonate is preferably about 120 to 310 parts by weight based on 100 parts by weight of the epoxy resin. If the combined amount of both is less than the above range, the flame retardancy of the obtained resin composition tends to be insufficient, while if the combined amount of both is more than the above range, the resulting resin composition It is not preferable because the viscosity increases.

In the present invention, other inorganic fillers may be used together with hydrated alumina and calcium carbonate. Such inorganic fillers include, for example, silicon dioxide, kaolin, clay,
Talc, glass fiber, glass beads, glass balloon,
Calcium silicate, barium sulfate, magnesium oxide,
Examples include titanium oxide, boron nitride, and zeolite.

In particular, it is preferable to use silicon dioxide. By adding silicon dioxide, the mechanical strength of the obtained cured resin can be improved, and the moisture resistance can be improved. In this case, for example, with respect to 100 parts by weight of the epoxy resin, silicon dioxide is used within a range not exceeding 75 parts by weight, but the total amount of hydrated alumina and silicon dioxide is 160 parts by weight.
Preferably it does not exceed parts by weight. When the total amount of hydrated alumina and silicon dioxide exceeds 160 parts by weight, the viscosity of the resin composition increases, and the impregnation tends to decrease,
Not preferred.

The total amount of the inorganic filler is usually about 80 to 400 parts by weight, preferably about 120 to 310 parts by weight, per 100 parts by weight of the epoxy resin. When the blending amount of the inorganic filler is less than the above range, the intended purpose of the present invention is difficult to be achieved.On the other hand, when the blending amount of the inorganic filler is more than the above range, the viscosity of the obtained resin composition increases. Therefore, it is not preferable in product design.

The organic phosphine compound (D) is applied as a curing accelerator. This is particularly effective for obtaining a low-viscosity composition.

As the organic phosphine compound, conventionally known compounds can be widely used, and examples thereof include a compound represented by the following general formula (VII).

[Wherein, R ⁸ , R ⁹ and R ¹⁰ may be the same or different, and each is a hydrogen atom, an alkyl group, a phenyl group, an aryl group such as a tolyl group, a cycloalkyl group such as a cyclohexyl group, (Here, R represents an alkylene group. R ′ and R ″ may be the same or different, and each represents a hydrogen atom, an aryl group such as an alkyl group, a phenyl group, a tolyl group, or a cycloalkyl group such as a cyclohexyl group. Where R ′ and R ″ are both hydrogen atoms), or an organic group containing an organic phosphine. However, this excludes the case where R ⁸ , R ⁹ and R ¹⁰ are all hydrogen atoms. Specific examples of such an organic phosphine compound include a third phosphine compound such as triphenylphosphine, tributylphosphine, tricyclohexylphosphine, and methyldiphenylphosphine; butylphenylphosphine;
A second phosphine compound such as diphenylphosphine, a first phosphine compound such as phenylphosphine and octylphosphine, and bis (diphenylphosphino) methane;
A third bisphosphine compound such as 2-bis (diphenylphosphino) ethane can be exemplified. In the present invention, the above-mentioned organic phosphine compounds can be used alone or in combination of two or more. Among the above organic phosphine compounds, aryl phosphine compounds are preferable, and triaryl phosphines such as triphenyl phosphine are particularly preferable.

The amount of the organic phosphine compound is usually about 0.2 to 5 parts by weight per 100 parts by weight of the epoxy resin, preferably
It is about 0.5 to 3 parts by weight. When the amount of the organic phosphine compound is less than the above range, the intended object of the present invention is difficult to be achieved, and even when the amount of the organic phosphine compound is more than the above range, there is no significant difference in effect, It is not preferable in terms of economy.

As a curing accelerator component, an organic phosphine compound and an amine compound can be used in combination.

By blending the amine compound, excellent moisture resistance can be imparted to a cast product of the epoxy resin composition.

As the amine compound, imidazoles and tertiary amines are recommended, and various compounds used in combination with an acid anhydride curing agent can be used.

As imidazoles, specifically, 2-ethyl-4-
Examples thereof include methyl imidazole, 2-methyl imidal, 1-benzyl-2-methyl imidazole, 2-undecylimidazole, 2-phenyl imidazole, 1-cyanoethyl-2-ethyl-4-methyl imidazole, and the like.

Specific examples of the tertiary amine include lauryl dimethylamine, dicyclohexylamine, dimethylbenzylamine, dimethylaminomethylphenol, 2,4,6-tris (N, N-dimethylaminomethyl) phenol (hereinafter referred to as “DMP”).
-30 ". ), 1,8-diazabicyclo (5,4,0)
Undecene-7 and the like are exemplified.

Modified products of these amine compounds by Lewis acid salts, organic acid salts, and adducts are also suitable compounds.

As the compounding amount of the amine compound, the epoxy resin 100
The amount is preferably about 0.2 to 5 parts by weight, more preferably about 0.5 to 3 parts by weight, per part by weight. When the compounding amount of the amine compound is less than the above range, the intended effect is difficult to be exhibited, while when the compounding amount of the amine compound is more than the above range, the pot life is shortened, and the calorific value of the cured product is reduced. The increase causes an increase in internal stress, and as a result, causes a problem such as distortion of a cured product.

Each compound (E) having the effect of suppressing or preventing the precipitation of the inorganic filler according to the present invention will be specifically exemplified.

Examples of the fatty acids (1) of the general formula (I) include saturated fatty acids such as capric acid, lauric acid, palmitic acid, stearic acid, arachidonic acid and behenic acid, oleic acid, erucic acid, linoleic acid and linolenic acid. Examples thereof include simple substances such as unsaturated fatty acids, hydroxystearic acid, and ricinoleic acid, and natural fatty acids containing these components, hydrogenated products thereof, isostearic acid, and the like.

(2) The dibasic acid [general formula (II)] includes sebacic acid, dodecane diacid, hexahydrophthalic acid, tetrahydrophthalic acid, 3-methyltetrahydrophthalic acid, 4-methyltetrahydrophthalic acid, 3-methyl Hexahydrophthalic acid, 4-methylhexahydrophthalic acid, nadic acid, phthalic acid and the like are exemplified. Monoesters thereof include monooleyl sebacate and monobutoxyethyl-3.
-Methyl-tetrahydrophthalate, monooleylhexahydrophthalate, mono-2-ethylhexyltetrahydrophthalate and the like can be exemplified.

Examples of the phosphite [3] of the general formula (III) include triphenyl phosphite, tris (nonylphenyl) phosphite, tri-n-butyl phosphite, tris (2-ethylhexyl) phosphite, and diphenyl monophosphite. Examples include decyl phosphite, hydrogenated bisphenol A phosphite polymer, trilauryl trithio phosphite, and trioleyl phosphite.

As the phosphite [general formula (IV)] of (4),
Examples thereof include dilauryl hydrogen phosphite and diphenyl hydrogen phosphite.

Examples of the amine (5) [general formula (V)] include dimethyldecylamine, dimethyllaurylamine, dimethylstearylamine, diethyllaurylamine, methyllaurylamine, laurylamine, sterylamine, dilaurylamine, and trilaurylamine. Is exemplified.

As the fatty acid amide (general formula (VI)) of (6), N, N
-Dimethyllaurylamide, N, N-dimethylstearylamide, stearic acid amide and the like.

Each of the above compounds may be used alone or in combination of two or more.

The appropriate compounding amount of the above compound is appropriately selected depending on the compounding amount of the inorganic filler, but is usually about 0.03 to 5 parts by weight, preferably about 0.05 to 3 parts by weight, per 100 parts by weight of the epoxy resin. If the amount is less than the above range, it is difficult to obtain a predetermined effect of preventing sedimentation.

The resin composition according to the present invention may optionally contain a flame retardant for the purpose of improving its flame retardancy.

Suitable flame retardants include, for example, antimony compounds such as antimony trioxide, halogen compounds such as hexabromobenzene, decabromodiphenyl oxide, tetrabromobisphenol A, brominated cresol monoglycidyl ether, and phosphorus compounds such as red phosphorus. Can be mentioned.

The number of added flame retardants is appropriately selected depending on the type of sled,
For example, 2 parts for red phosphorus per 100 parts by weight of epoxy resin
About 50 parts by weight, about 3 to 40 parts by weight for antimony trioxide, and about 5 to 50 parts by weight for a halogen compound. These flame retardants may be used alone or in combination of two or more.

Further, the resin composition of the present invention includes natural or synthetic waxes, metal soaps, fatty acid amides, esters, release agents such as paraffins, coloring agents such as carbon black,
A silane coupling agent, a diluent, an antifoaming agent, a plasticizer, an antioxidant and the like can be appropriately compounded.

The resin composition according to the present invention is prepared, for example, as follows.

That is, a predetermined amount of an epoxy resin and an inorganic filler are mixed and processed at normal temperature or under heating with a mixer such as a Henschel mixer, a Banbury mixer, an extruder, a hot roll, or a kneader, and the carboxylic anhydride-based curing agent is added thereto. ,
Predetermined amounts of an organic phosphine-based curing accelerator, an anti-settling agent, and, if necessary, a flame retardant may be added. At this time, the mixing order of the raw material components does not matter, and the resin composition may be prepared by mixing predetermined raw materials at once. Further, if necessary, the system may be depressurized and degassed at room temperature or under heating.

The epoxy resin composition thus obtained has no sedimentation of the inorganic filler despite having a low viscosity, and as a result, the impregnating property is good, and the insulating property, the moisture resistance, the curability,
A cured product excellent in various properties such as thermal shock resistance, thermal conductivity, and flame retardancy can be obtained.

Therefore, the epoxy resin composition of the present invention can be effectively used in fields where insulating properties are particularly required, such as casting of various electric components such as coils and capacitors, in addition to casting of flyback transformers.

EXAMPLES Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples.

The properties of each epoxy resin composition were evaluated by the following methods.

Viscosity (Poise, P): Measured with a B-type viscometer under a temperature condition of 25 ° C.

Impregnating property: After impregnating the epoxy resin composition on a bobbin wound with 200 enamel wires having a diameter of 40 μm at 200 ° C. under a vacuum of 3 mmHg at 50 ° C., the cured product is cured at 80 ° C. for 3 hours and then at 110 ° C. for 3 hours Obtained. Next, the cured product was cut perpendicular to the winding, and the impregnation rate was calculated according to the following equation.

Impregnation ratio (%) = [1- (number of voids in cut surface / number of windings in cut surface)] × 100 Hygroscopicity of cured product: epoxy resin composition at 80 ° C. for 3 hours and then at 110 ° C. for 3 hours Pressure cooker test (measurement condition 1: 121 ° C, 1.2 kg)
/ cm ² , 50 hours).

Cured product homogeneity: epoxy resin composition height 80mm, diameter
Hardened into a 15mm column, cut into three layers: upper, middle, lower
Each specific gravity was measured according to 6911. Next, the degree of suppression of sedimentation of the inorganic filler during curing was evaluated based on the value obtained by subtracting the specific gravity of the upper layer portion from the specific gravity of the lower layer portion.

Flame retardancy: A 1.5 mm thick cured product was subjected to a vertical burning test according to UL94 standard.

Example 1 80 parts by weight of bisphenol A type epoxy resin (epoxy equivalent 190) as epoxy resin (1), 20 parts by weight of diglycidyl ether type diluent (epoxy equivalent 150) as epoxy resin (2), and hydration as inorganic filler A main component obtained by stirring and mixing 130 parts by weight of alumina (average particle diameter 3.5 μ), 60 parts by weight of calcium carbonate (average particle diameter 3 μm), 30 parts by weight of hexabrobenzene as a flame retardant, and 10 parts by weight of antimony trioxide; A curing agent liquid obtained by dissolving 82 parts by weight of Me-THPA which is a carboxylic anhydride (Rikacid MT500: manufactured by Shin Nippon Rika Co., Ltd.), 2 parts by weight of triphenylphosphine, and 0.5 part of oleic acid as an anti-settling agent was used. This was mixed to obtain an epoxy resin composition. The viscosity, impregnating property, hygroscopicity, homogeneity and flame retardancy of the cured product were measured according to the methods described above. Table 1 shows the obtained results.

Examples 2 to 7 Epoxy resin (1), epoxy resin (2), Me-THP
A, Me-HHPA (Ricacid MH-700: Shin Nippon Rika Co., Ltd.)
), Hydrated alumina, calcium carbonate, silicon dioxide (average particle size 9μ), a flame retardant, a curing accelerator, and an anti-settling agent in the composition shown in Table 1 and an epoxy resin composition as in Example 1. A product was prepared and various properties of the product were measured. Table 1 shows the obtained results.

Examples 8 to 16 Epoxy resin compositions were obtained in the same manner as in Example 1, except that the type and amount of the anti-settling agent were variously changed. The viscosity of this formulation and the homogeneity of the cured product (the degree of suppression of sedimentation of the inorganic filler) were measured. Table 2 shows the obtained results.

Comparative Example 1 An epoxy resin composition was obtained and its properties were evaluated in the same manner as in Example 1 except that DMP-30 was used as a curing accelerator and no anti-settling agent was added. Table 1 shows the obtained results.

Comparative Example 2 An epoxy resin composition was obtained and its properties were evaluated in the same manner as in Example 5, except that DMP-30 was used as a curing accelerator, calcium carbonate was not used, and an antisettling agent was not used. Table 1 shows the obtained results.

Comparative Example 3 An epoxy resin composition was obtained in the same manner as in Example 3 except that DMP-30 was used as a curing accelerator and no anti-settling agent was used, and the properties were evaluated. Table 1 shows the obtained results.

Comparative Example 4 An epoxy resin composition was obtained and its properties were evaluated in the same manner as in Example 1 except that oleic acid was not used as an antisettling agent. Table 1 shows the obtained results.

Comparative Example 5 An epoxy resin composition was obtained in the same manner as in Example 1 except that the type and amount of the anti-settling agent were variously changed. The viscosity of the formulation and the homogeneity of the cured product were measured. Table 2 shows the obtained results. Caproic acid in Comparative Example 6 and dimethylhexylamine in Comparative Example 7 were each compounded as an example of a compound having a short alkyl chain length. Comparative Example 8
"Erosil # 200" blended in the above is ultra-fine silicon dioxide manufactured by Nippon Aerosil Co., Ltd.

[Effect of the Invention] Although the liquid epoxy resin composition according to the present invention has a low viscosity, it can prevent or suppress the settling of the inorganic filler during storage and heat curing. Therefore, when casting electric components such as a flyback transformer and a switching transformer, the impregnation property is improved, and the obtained cured product is uniform and has excellent moisture resistance.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location C08K 5/10 C08K 5/10 5/17 5/17 5/20 5/20 5/51 NLB 5 / 51 NLB C08L 63/00 NKC C08L 63/00 NKC

Claims (1)

(57) [Claims] 1. A liquid epoxy resin composition comprising the following components (A) to (E) as essential components, and optionally a component (F). (A) an epoxy resin, (B) a liquid carboxylic anhydride, (C) an inorganic filler containing hydrated alumina and calcium carbonate, (D) an organic phosphine compound, and (E) a compound represented by (1) to (8). One or two of
A mixture of more than one species, (7) Dimer acid (8) Rosin [In each of the above general formulas, R ¹ is a linear or branched C 9-24 carbon atom which may have a hydroxyl group.
Represents an alkyl group or an alkenyl group. R ² represents a linear or branched alkyl group having 6 to 26 carbon atoms, a cycloalkyl group, a cycloalkenyl group, or an aryl group. R ³ , R ⁴ and R ⁵ are a hydrogen atom or a linear or branched carbon atom which may be the same or different and has 1 to 26 carbon atoms.
Represents an alkyl group, alkenyl group, cycloalkyl group, cycloalkenyl group, aryl group and alkylene oxide adduct thereof. However, all of R ³ , R ⁴ and R ⁵ are not hydrogen atoms. R ⁶ and R ⁷ may be the same or different and each have a hydrogen atom or a linear or branched carbon atom which may have a hydroxyl group.
-24 represents an alkyl group or an alkenyl group. (F) One or a mixture of two or more of an antimony compound, a halogen compound and a phosphorus compound.